in arrears idiom
拖欠
owing money that should have been paid already
My account is badly in arrears. 我账户上的欠款太多了。
They are in arrears on/with their mortgage payments. 他们的按揭贷款逾期未还。
后付（工作一段时间后支付薪水）
If someone is paid in arrears, they are paid at the end of the period of time during which the money was earned.
I'm paid a week in arrears. 我每周末领薪水。